I have had this foundation since mid-december and have been using it for about a month, I put off reviewing it over and over because I really wasn't sure what I made of it.
Giorgio Armani Luminous Silk Foundation is an expensive one at £34 a bottle, but it's something you wear every day, so it's worth investing in a good foundation. I always try to wear a good foundation because I find a lot of the high street colours just don't suit me, break me out or look cakey or even flakey. This one looks so natural I had a problem defining it because it just looked like, well, my skin. But better.
If you're looking for something for work this one is perfect. There is coverage but not so much that I would call it a full-coverage foundation, if I call it medium it might sound thicker than it actually is. See my dilema with this foundation?!
4.5 is a yellowy light olive based colour. A little goes a long way (one pump) and in fact if you use too much it starts to look obvious, you just don't need it. My skin is really difficult at the moment and I wouldn't say this covers blemishes, but teamed with my medium Collection concealer, the two work perfectly. It's not drying or heavy and the colour match is perfect for me.
I used to use Chanel Vita Lumiere and I wouldn't say I like it quite as much or that it is as dewy, but it comes very close!